Littérature scientifique sur le sujet « Sistemi antiossidanti »

2014-2015
Lifestyle and food choices have an important role in the onset and in the prevention of some diseases. The assumption of some food-related molecules can have different effects on human health; for example, the antioxidants can lower the risk of some diseases, while the mycotoxins, contaminants of cereals and milk, could be involved in the rise of Autism Spectrum Disorders in genetically predisposed patients. The aim of this project was to identify possible protein targets for both mycotoxins and antioxidants, and to understand the mechanisms of actions underlying their effects. Protein targets were searched through a reverse docking approach using idTarget web-server. Subsequently, molecular docking using AutoDock 4.2 between the ligands (mycotoxins and antioxidants) and each of the selected protein targets was performed, in order to identify their binding sites. The interactions between mycotoxins and possible protein targets with good predicted energies were selected in order to validate them experimentally by means of techniques such as fluorescence techniques and MST. The interactions between antioxidants and possible protein targets with good predicted energies were selected to perform functional analysis via bioinformatics tools. The fluorescence techniques confirm that some mycotoxins bind the Acetylcholinesterase and Neuroligin-4, X linked, which is involved in Autism disease. The functional analysis results about the protein targets of the antioxidants suggests that chemopreventive effects of antioxidants in human pathologies, in particular for colon cancer, may be related to the possible interference of these molecules with the activity of nucleotide metabolism and methylation enzymes, similarly to some classes of anticancer drugs.[edited by Autor]
XIV n.s.

I sistemi antiossidanti e della biotrasformazione sono noti per la sensibilità di risposta agli stress ambientali, pertanto negli organismi marini vengono usati come biomarkers della contaminazione, misurati a livello di attività catalitica e/o di espressione genica. Tuttavia, i meccanismi di modulazione di questi sistemi e le relazioni tra risposte trascrizionali e funzionali sono ancora in parte sconosciuti nelle specie marine. Per approfondire tali meccanismi sono state utilizzate due specie, l’anguilla A. anguilla e il mitilo M. galloprovincialis, rappresentative di vertebrati ed invertebrati marini. Esposizioni di laboratorio a miscele di contaminanti hanno evidenziato differenze di risposta dipendenti da specie, tessuto e sistema enzimatico analizzato. Le risposte catalitiche degli enzimi della biotrasformazione sono risultate comparabili alle corrispondenti risposte trascrizionali; le risposte antiossidanti hanno mostrato una mancanza di corrispondenza tra variazioni trascrizionali e catalitiche, suggerendo meccanismi di regolazione indipendenti a livello biochimico e genico. Nei mammiferi, i geni antiossidanti sono regolati dal fattore di trascrizione Nrf2 e dal suo inibitore Keap1. L’identificazione di Nrf2 e Keap1 in A. anguilla ha confermato che tale via di regolazione è conservata nelle specie marine. I risultati ottenuti in condizioni sperimentali di pressione ossidativa evidenziano la regolazione coordinata dei geni antiossidanti e l’attivazione trascrizionale di Nrf2 e Keap1, suggerendo inoltre l’importanza della sintesi de novo di Nrf2 per l’induzione prolungata dei geni target e un possibile ruolo di Keap1 nello spegnimento della risposta. Nel complesso, i risultati indicano che le risposte trascrizionali possono essere sensibili ma non corrispondono necessariamente a effetti funzionali, risultando più utili come biomarkers “di esposizione” che “di effetto”, e ampliano la conoscenza dei meccanismi di risposta antiossidante nelle specie marine.
Antioxidant and biotransformation pathways are known for their responsiveness to environmental stressors, hence they are used in marine organisms as biomarkers of contamination, measured at level of both catalytic activity and gene transcription. However, the mechanisms of modulation of these systems and the relationships between transcriptional and functional responses are still partially unclear in non-mammalian species. To investigate such mechanisms two model species were selected, the eel A. anguilla and the mussel M. galloprovincialis, as representative of vertebrate and invertebrate marine organisms. Laboratory exposures to complex mixtures of contaminants revealed different responses dependent on the species, the tissue and the specific enzymatic system. Catalytic responses of biotransformation enzymes were often comparable to the corresponding transcriptional responses; antioxidant responses frequently displayed a lack of correspondence between transcription and catalytic level, suggesting independent mechanisms of regulation at molecular and biochemical levels. In mammalian, antioxidant genes are regulated by the Nrf2 transcription factor and its inhibitor Keap1. The identification of Nrf2 and Keap1 in A. anguilla confirmed that such pathway of regulation of antioxidant defences is conserved in marine species. Oxidative pressure generated in experimental conditions leaded to the coordinate regulation of antioxidant genes and transcriptional activation of Nrf2 and Keap1 genes. Furthermore, our results suggest the importance of Nrf2 de novo synthesis for the protracted induction of target genes, and a possible role for Keap1 in switching off the response. The overall results indicated that transcriptional responses might be sensitive but do not necessarily correspond to functional changes, being more useful as “exposure” rather than “effect” biomarkers, and provided useful insights on mechanisms of antioxidant responses in marine species.

Il lavoro si è articolato in due parti: sintesi di una molecola antiossidante (lipofenolo), che in prospettiva dovrà essere prodotta a partire da sottoprodotti dell’industria alimentare. La molecola ottenuta, già studiata nello sviluppo di emulsioni, è stata in questo lavoro testata nella formulazione di prodotti da forno, nei quali l’ossidazione lipidica è un processo difficilmente controllabile, se non con l’impiego di grassi saturi, come palma o strutto e sego. L’ossidazione incide profondamente sulla qualità e sulla sicurezza dell’alimento. È per questo che numerosi studi si sono rivolti, in questi anni, verso i meccanismi di antiossidazione nei sistemi reali. Partendo da una panoramica sui sottoprodotti della filiera alimentare, in questo lavoro si è ottimizzata una reazione di lipofilizzazione tra tirosolo e acido oleico e si è impiegato il prodotto nella formulazione tarallini per verificarne l’effettiva capacità di allungare la shelf life del prodotto ritardando l’insorgenza dell’ossidazione, con esiti più che soddisfacenti evidenziati dai dati ottenuti tramite tecniche di ossidazione forzata (Oxitest®) , analisi della componente volatile (SPME-GC-MS) e misurazione del numero di perossido.

The olive oil extraction industry is responsible for the production of high quantities of vegetation waters, represented by the constitutive water of the olive fruit and by the water used during the process. This by-product represent an environmental problem in the olive’s cultivation areas because of its high content of organic matter, with high value of BOD5 and COD. For that reason the disposal of the vegetation water is very difficult and needs a previous depollution. The organic matter of vegetation water mainly consists of polysaccharides, sugars, proteins, organic acids, oil and polyphenols. This last compounds are the principal responsible for the pollution problems, due to their antimicrobial activity, but, at the same time they are well known for their antioxidant properties. The most concentrate phenolic compounds in waters and also in virgin olive oils are secoiridoids like oleuropein, demethyloleuropein and ligstroside derivatives (the dialdehydic form of elenolic acid linked to 3,4-DHPEA, or p-HPEA (3,4-DHPEA-EDA or p-HPEA-EDA) and an isomer of the oleuropein aglycon (3,4-DHPEA-EA). The management of the olive oil vegetation water has been extensively investigated and several different valorisation methods have been proposed, such as the direct use as fertilizer or the transformation by physico-chemical or biological treatments. During the last years researchers focused their interest on the recovery of the phenolic fraction from this waste looking for its exploitation as a natural antioxidant source. At the present only few contributes have been aimed to the utilization for a large scale phenols recovery and further investigations are required for the evaluation of feasibility and costs of the proposed processes. The present PhD thesis reports a preliminary description of a new industrial scale process for the recovery of the phenolic fraction from olive oil vegetation water treated with enzymes, by direct membrane filtration (microfiltration/ultrafiltration with a cut-off of 250 KDa, ultrafiltration with a cut-off of 7 KDa/10 KDa and nanofiltration/reverse osmosis), partial purification by the use of a purification system based on SPE analysis and by a liquid-liquid extraction system (LLE) with contemporary reduction of the pollution related problems. The phenolic fractions of all the samples obtained were qualitatively and quantitatively by HPLC analysis. The work efficiency in terms of flows and in terms of phenolic recovery gave good results. The final phenolic recovery is about 60% respect the initial content in the vegetation waters. The final concentrate has shown a high content of phenols that allow to hypothesize a possible use as zootechnic nutritional supplements. The purification of the final concentrate have garanteed an high purity level of the phenolic extract especially in SPE analysis by the use of XAD-16 (73% of the total phenolic content of the concentrate). This purity level could permit a future food industry employment such as food additive, or, thanks to the strong antioxidant activity, it would be also use in pharmaceutical or cosmetic industry. The vegetation water depollutant activity has brought good results, as a matter of fact the final reverse osmosis permeate has a low pollutant rate in terms of COD and BOD5 values (2% of the initial vegetation water), that could determinate a recycling use in the virgin olive oil mechanical extraction system producing a water saving and reducing thus the oil industry disposal costs .

The olive oil extraction industry is responsible for the production of high quantities of vegetation waters, represented by the constitutive water of the olive fruit and by the water used during the process. This by-product represent an environmental problem in the olive’s cultivation areas because of its high content of organic matter, with high value of BOD5 and COD. For that reason the disposal of the vegetation water is very difficult and needs a previous depollution. The organic matter of vegetation water mainly consists of polysaccharides, sugars, proteins, organic acids, oil and polyphenols. This last compounds are the principal responsible for the pollution problems, due to their antimicrobial activity, but, at the same time they are well known for their antioxidant properties. The most concentrate phenolic compounds in waters and also in virgin olive oils are secoiridoids like oleuropein, demethyloleuropein and ligstroside derivatives (the dialdehydic form of elenolic acid linked to 3,4-DHPEA, or p-HPEA (3,4-DHPEA-EDA or p-HPEA-EDA) and an isomer of the oleuropein aglycon (3,4-DHPEA-EA). The management of the olive oil vegetation water has been extensively investigated and several different valorisation methods have been proposed, such as the direct use as fertilizer or the transformation by physico-chemical or biological treatments. During the last years researchers focused their interest on the recovery of the phenolic fraction from this waste looking for its exploitation as a natural antioxidant source. At the present only few contributes have been aimed to the utilization for a large scale phenols recovery and further investigations are required for the evaluation of feasibility and costs of the proposed processes. The present PhD thesis reports a preliminary description of a new industrial scale process for the recovery of the phenolic fraction from olive oil vegetation water treated with enzymes, by direct membrane filtration (microfiltration/ultrafiltration with a cut-off of 250 KDa, ultrafiltration with a cut-off of 7 KDa/10 KDa and nanofiltration/reverse osmosis), partial purification by the use of a purification system based on SPE analysis and by a liquid-liquid extraction system (LLE) with contemporary reduction of the pollution related problems. The phenolic fractions of all the samples obtained were qualitatively and quantitatively by HPLC analysis. The work efficiency in terms of flows and in terms of phenolic recovery gave good results. The final phenolic recovery is about 60% respect the initial content in the vegetation waters. The final concentrate has shown a high content of phenols that allow to hypothesize a possible use as zootechnic nutritional supplements. The purification of the final concentrate have garanteed an high purity level of the phenolic extract especially in SPE analysis by the use of XAD-16 (73% of the total phenolic content of the concentrate). This purity level could permit a future food industry employment such as food additive, or, thanks to the strong antioxidant activity, it would be also use in pharmaceutical or cosmetic industry. The vegetation water depollutant activity has brought good results, as a matter of fact the final reverse osmosis permeate has a low pollutant rate in terms of COD and BOD5 values (2% of the initial vegetation water), that could determinate a recycling use in the virgin olive oil mechanical extraction system producing a water saving and reducing thus the oil industry disposal costs .

Tutti i materiali, colorati e non, sono soggetti all’invecchiamento causato dall’esposizione prolungata alla luce solare. A causa principalmente di reazioni radicaliche fotoiniziate, i materiali si deteriorano con conseguente perdita delle caratteristiche iniziali con cui sono stati creati. Per arginare questo problema, vengono utilizzate molecole apposite con caratteristiche antiossidanti che spengono le reazioni radicaliche o si sacrificano al posto del materiale che proteggono. Su un particolare materiale, però, queste molecole non vengono utilizzate: si tratta della fibra cellulosica colorata. In questo ambito, infatti, si preferisce l’utilizzo di pigmenti colorati già intrinsecamente stabili alla luce solare, che non hanno quindi bisogno dell’applicazione di antiossidanti. I pigmenti colorati, tuttavia, sono molto più costosi dei coloranti organici. In questo progetto di tesi si è deciso quindi di condurre uno studio sulla possibile applicazione di molecole antiossidanti su substrati cartacei colorati con coloranti organici di diversa natura e sul loro effetto in base all’esposizione del substrato colorato alla luce solare. Sono state studiate, in particolare, cinque molecole antiossidanti diverse e se ne è sintetizzata una sesta con caratteristiche tali da approfondire i risultati precedentemente ottenuti.

Questo lavoro di tesi è stato finalizzato allo studio dell’applicabilità e dell’efficacia di una modalità di confezionamento dell’olio extra vergine di oliva (EVO) in grado di raggiungere due obiettivi: - il prolungamento della shelf-life dell’olio d’oliva grazie ad un’azione protettiva del packaging dalla radiazione luminosa; - l’ottenimento di un’estetica accattivante che consenta al consumatore di apprezzare colore e livello del prodotto contenuto. È stata, quindi, testata l’efficacia di un film protettivo trasparente, termoretraibile, stampabile e con effetto barriera contro le radiazioni UV applicato su bottiglie in vetro trasparente, confrontando i risultati ottenuti con quelli raccolti per campioni conservati in bottiglie in vetro scuro e trasparente. Per la realizzazione di questo studio sono stati utilizzati due EVO monovarietali e per ognuno di questi sono state confrontate tre tipologie di confezionamento: vetro scuro, vetro trasparente rivestito con pellicola, vetro trasparente. Per simulare un processo di “invecchiamento accelerato” le bottiglie sono state poste in un termostato (20 °C) all’interno del quale sono state istallate delle lampade in grado di illuminare le bottiglie in continuo e i campioni erano monitorati ad intervalli regolari (5, 10 e 15 settimane). Le determinazioni analitiche svolte (titrimetriche, spettrofotometriche, cromatografiche e sensoriali) hanno riguardato i principali parametri quali-quantitativi correlati allo stato idrolitico (acidità libera, digliceridi) ed ossidativo (numero di perossidi) degli oli d’oliva, nonché relativi alle molecole antiossidanti (contenuto in fenoli totali e tocoferoli) ed agli attributi sensoriali. I risultati ottenuti da queste prove esplorative hanno evidenziato come l’applicazione di sleeve additivate con anti-UV su bottiglie in vetro trasparente possa costituire una valida modalità di confezionamento dell’olio EVO, anche se saranno necessarie ulteriori conferme ed approfondimenti.